Introduction. This paper presents a comprehensive analytical study of the buckling of I-section columns with web depth varying linearly along the column length. Closed-form solutions were obtained using the analytical Bubnov – Galerkin method and direct integration of the differential equation of the deflected axis for the member. The effectiveness of the Bubnov – Galerkin method is assessed for determining the effective length factor of a pinned centrally compressed column with variable stiffness. An alternative view of the buckling problem for a variable-stiffness column is also proposed, and the solution is supplemented by reconsidering the basis function based on parameter ψ1. This approach provides an independent analysis of the buckling problem of I-section columns with a tapered web. The obtained values of the effective length factor are close to each other, and the mean relative error does not exceed 5 %.

Materials and methods. The analytical Bubnov – Galerkin method and direct integration of the differential equation were used.

Results. Using analytical methods, closed-form equations for the effective length factor of an I-section column with variable stiffness were obtained. In total, three calculation formulas are presented.

Conclusions. The proposed formulas for the effective length factor make it possible to perform a stability calculation of a pinned I-section column with linearly varying web depth along its length. The study also provides additional information on eccentrically loaded I-section members with a tapered web.

Introduction. The paper investigates nonlinear oscillations of the Duffing harmonic oscillator, which are relevant for assessing the stability of mechanical and structural systems with elastic and damping components. The study’s relevance is linked to understanding the transition from regular to chaotic oscillations in seismic isolation and vibration control elements. The novelty lies in applying the Rosenstein method to quantitatively estimate the exponent-like quantity e1, replacing the qualitative approach used in Ueda’s classical studies (1979).

Materials and methods. The oscillator is described by the equation ẍ + kẋ + x3 = Bcos(ωt). Numerical integration was performed in MATLAB using the custom “+ueda” package. The dynamics were analyzed through Poincaré sections and by calculating the exponent-like value e1 using the Rosenstein algorithm, which tracks divergence of nearby trajectories in the reconstructed phase space.

Results. It is shown that increasing the excitation amplitude B (at k = 0.10) drives the system from periodic to chaotic motion via quasi-periodic states. Increasing the damping k (at B = 12.0) suppresses chaotic oscillations, restoring regular behaviour. The dependencies e1(B) and e1(k), refine the boundaries of chaos onset compared to Ueda’s results, identifying critical intervals Bc = 11.9–12.2 and kc = 0.26–0.30.

Conclusions. The results of the study confirmed the applicability of the Rosenstein method for the quantitative identification of chaotic modes in Duffing systems. The data obtained refine the boundaries of the transitions, in line with classical studies, and can be used in the design of seismic isolators and vibration-damping devices where it is necessary to avoid chaotic oscillations.

Introduction. Construction of facilities on riverbanks is a costly task with limited demand. A number of supplementary issues should be taken into account when developing design solutions for their construction. These issues include the development of slope stabilization measures and protection of the soil mass from erosion. The technical and technological feasibility of implementing such projects under conditions of hazardous slope processes should also be considered in the course of design development.

Materials and methods. The variety of conditions under which facilities on riverbanks are constructed limits the applicability of standard solutions; as a result, an individual set of solutions becomes necessary for each facility, beginning with the fundamental selection of technological and structural solutions. The geotechnical aspects of designing engineering protection facilities for the Volga riverbank slope near the village of Cherkasovo are considered within the framework of an improvement project, taking into account the technological and structural features of the site.

Results. Numerical modeling of construction operations at the existing project site was performed to assess slope stability after the implementation of protective measures. The analysis provided stability assessment results for the soil mass.

Conclusions. The most significant factors influencing the selection of optimal structural solutions were analyzed and presented, and possible options for specific geotechnical solutions were proposed.

Introduction. The installation of precast reinforced concrete piles by static jacking is generally considered a low-impact technology; however, when applied on a large scale in water-saturated clay soils, a significant heave of both the surrounding soil mass and adjacent buildings is observed. An engineering method is presented that enables a preliminary assessment of the extent of the influence zone and prediction of deformations in adjacent structures.

Materials and methods. The proposed approach is based on an analytical solution to the problem of soil consolidation around a pile; it employs a model of radial pore-water flow. A homogeneous pile field is represented as an equivalent cavity whose volume is equal to the volume of the displaced soil. The radius of the influence zone is defined as the distance beyond which the excess pore water pressure is zero. The heave of the surrounding soil mass is evaluated using a layer-by-layer summation technique.

Results. To assess the applicability of the procedure, the results of the analytical solution were compared with the geotechnical monitoring data. The predicted values demonstrated satisfactory agreement with the in-situ measurements. The applicability of empirical correlations for estimating the undrained shear strength of soil within the proposed approach was evaluated.

Conclusions. The procedure for estimating deformations of the soil mass and the influence zone during pile installation by static jacking has been verified against field observations in Saint Petersburg, and its suitability is confirmed for engineering calculations at preliminary design stages. A key condition for the reliability of the prediction is the use of undrained shear strength parameters obtained from laboratory triaxial tests. To ensure reliability and to account for complex engineering and geological conditions, final recommendations should be developed on the basis of numerical modeling.

Introduction. With the growth of plastic production and the accumulation of plastic waste, recycling is becoming increasingly important. The incorporation of recycled polymers in the construction industry promotes a more rational use of natural resources and can reduce the cost of building materials. This article reviews studies examining changes in the physical and mechanical properties of concrete composites containing polypropylene (PP) and high-density polyethylene (HDPE) waste used as partial replacements for fine and coarse aggregates.

Materials and methods. A systematic analysis, generalization, and synthesis of data from open-access Russian and international sources were performed. Practical experience in the use of recycled polymers for producing concrete composites was examined to assess the effect of replacing conventional aggregates with PP and HDPE waste on the strength properties of concrete.

Results. Data on the characteristics of plastic waste, technologies for manufacturing concrete composites, and the resulting material properties were systematized. The authors conducted a comparative analysis of changes in the strength characteristics of concrete depending on the parameters of natural aggregate replacement with recycled PP and HDPE.

Conclusions. Analysis of the scientific literature on the application of plastic waste in concrete production demonstrates the significant potential of this research area. The use of recycled HDPE and PP appears particularly feasible because of their widespread availability and ease of processing. When these wastes are incorporated into concrete mixtures, material strength generally decreases with increasing waste content. However, in some cases, strength improvements compared with control specimens have been reported. Further research on the physical and mechanical properties of concrete containing combined PP and HDPE waste, as well as the determination of optimal component proportions and production technologies, remains relevant.

Introduction. Riverbank erosion is a complex, multidimensional process that influences fluvial landscapes, sediment fluxes, and stability of eco-systems. It has affects infrastructure and livelihoods, particularly in riparian and deltaic regions. This topic has attracted considerable scholarly attention due to its environmental and socio-economic implications under the pressures of global change.

Materials and methods. This review synthesizes more than 40 years of interdisciplinary research on riverbank erosion. A systematic literature search was conducted across major scientific databases, focusing on seven thematic areas including erosion mechanisms, measurement, modeling, vegetation, climate, and socio-economic impacts. Methodologies include high-resolution remote sensing, sediment fingerprinting, and process-based modeling tools such as BSTEM.

Results. The analysis reveals a dynamic interplay between hydraulic forces, soil properties, vegetation traits, climate variability, and human interventions. Key methodological advances have improved monitoring and prediction, yet standardization and integration across spatial and disciplinary scales remain limited. Socio-economic consequences, including displacement and infrastructure loss, are still underrepresented in modeling frameworks.

Conclusions. The review highlights critical knowledge gaps, particularly regarding the impact of climate change, invasive species, and cross-scale human activity. It advocates for a systems-based, interdisciplinary approach to improve erosion modeling and support resilient, equitable river management strategies.

Introduction. Reports on the flooding of urban streets regularly appear in the mass media. Such flooding is caused by climate change, by the insufficient conveyance capacity of urban drainage systems relative to the stormwater runoff flow rates generated, or by the complete absence of such systems. The subject of the study is surface runoff management, including collection, regulation of discharge to centralized sewerage systems, treatment, and subsequent discharge to receiving water bodies. The aim of the study is to optimize surface runoff management in urban environments through the installation of bioengineering structures.

Materials and methods. The study included an analytical review of regulatory documents and the results of Russian and international research and development activities addressing the management of surface runoff generated in urban environments. Data on the treatment efficiency of bioengineering structures were analyzed to assess the feasibility of discharging treated surface runoff into receiving water bodies.

Results. The main types of bioengineering structures for surface runoff management include rain gardens, vegetated roofs, hydro-botanical sites, bioswales. The amount of runoff depends on the soil thickness, soil composition, and the presence or absence of drainage. The removal efficiency for BOD ranged from 67 to 98 %, for COD — from 70 to 92 %, and for petroleum hydrocarbons — from 40 to 100 %. Using surface runoff for non-potable urban water supply can reduce demand on centralized water supply systems by 30–60 %.

Conclusions. It should be noted that the performance of bioengineered structures in terms of surface runoff retention and treatment should be assessed individually for each design solution in order to prevent adverse environmental impacts.

Introduction. Water supply systems are strategically important, energy-intensive, capital-intensive, and highly inertial systems. These characteristics result in a virtually complete lack of adaptive mechanisms for optimizing their operating conditions. Water supply disruptions are caused by the unpredictability of system development patterns and by the lack of algorithms for determining the probability of population migration tracks, specific water consumption and system failure rates. Demonstrative examples of such errors include group water supply systems built more than 60 years ago. Due to population outflow and industrial decline, many water supply systems remain underground but are no longer operated because of insufficient consumer demand. At the same time, systems in large cities and megalopolises are overloaded because of active infill development, which causes imbalances in utility networks. Paradoxically, statistics for the past 20 years show that specific water consumption has decreased by almost half.

Materials and methods. When designing advanced water supply schemes, uncertainties related to future water demand and electricity unit costs should be considered, and system development trajectories that minimize economic and technological risks should be selected.

Results. A decision-making criteria matrix can be applied to select the parameters of a future water supply system under conditions of uncertainty related to population size, unit water demand, electricity costs, and other factors.

Conclusions. A multivariant design approach should be adopted, treating water consumption, population size, and electricity cost as fuzzy and uncertain variables and selecting options that minimize life-cycle cost risks.

Introduction. The role of ports in supporting economic growth, global value chains, and logistics flows is undeniable. While inefficient ports slow down trade, disrupt transport flows, and increase costs, future-ready infrastructure attracts investment and supports economic development. However, port construction is costly and involves lengthy periods of planning, consultation and construction. Port operation and management also require a specialized workforce and expertise. The purpose of this paper is to examine approaches to optimizing the parameters of technological processes and systems for organizing the construction of port facilities.

Materials and methods. The study is based on systematic and synthetic approaches, including theoretical analysis of the literature, generalization of existing models and approaches to the construction of port facilities, and mathematical modeling. In addition, the work used methods of stochastic and adaptive optimization, which take into account the uncertainty of technological, logistical, and natural factors in the process of constructing port facilities.

Results. The paper proposes an intelligent adaptive model for multi-criteria optimization of organizational and technological systems for the construction of port facilities. The author’s model provides robust, adaptive, and self-learning management of port facility construction, minimizing deviations from the plan, increasing the efficiency of resource use, reducing time and risks, and integrating multi-criteria objectives in conditions of high stochasticity and limited spatial resources.

Conclusions. The model proposed in this work provides a transition from static planning of construction work to adaptive management that is resistant to actual technological deviations. The practical application of this model will allow not only to adjust the schedule, but also to accumulate verified data for updating standards and developing future practices for the construction of port facilities.

Introduction. The article addresses the relevant issue of how decisions made for a  construction organization project (COP) and a work organization project (WOP) affect the organizational and technological reliability of construction (OTR). It examines the relationship between the statutory regulation of organizational and technological schemes (OTS) within the COP (WOP), the rationality of organizational and technological decisions made, and their effect on OTR.

Materials and methods. The key provisions of regulatory, legal, and design documentation were analyzed to identify uncertainties related to the organization of construction. The authors clarified definitions of the concepts “organizational and technological reliability”, “organizational and technological scheme”, “methods of work execution”, “demolition”, and “dismantling”. The article describes in detail an approach to substantiating the OTS within the COP (WOP), as the basis of a rational and safe method of work performance that enhances the organizational and technological reliability of construction. Two examples are used to substantiate the rational methods of work execution and their integration into the OTS.

Results. Uncertainties in the use of concepts in regulatory, legal, and design documentation that may adversely affect the organizational and technological reliability of construction during project preparation have been addressed. The proposed approach and the cases considered in the article determine the structure of the OTS, help to identify and use specific source data for developing the OTS for the erection and dismantling of a structure or part of a structure, and to define rational forms of textual and graphical representation of the OTS within organizational and technological documentation.

Conclusions. The proposed approaches to substantiating and presenting the organizational and technological scheme (OTS) within the construction organization project (COP) and the work organization project (WOP), together with the analysis of the regulatory and methodological framework for organizational and technological design, carried out in conjunction with the interpretation of the key provisions of the theory of organizational and technological reliability, serve as a theoretical basis for improving the organizational and technological reliability of construction work performance.

Introduction. This paper addresses the problem of optimizing building placement on land plots of complex shape at the early stages of design, when initial data are limited and the requirements are specified as a system of geometric constraints and quality targets. The relevance of the study stems from the high labor intensity of manually preparing layout alternatives and the need for an objective comparison of layout solutions for plots with irregular boundary geometry. The scientific novelty of the study lies in the formalization of the problem statement and the comparative study of heuristic and intelligent methods within a single computational protocol.

Materials and methods. The experimental dataset includes 79 objects and covers the comparison of 18 AI methods for generating and selecting planning solutions. Regression models were used to select alternatives; these models were trained and verified by grouping the objects. Complex-shaped areas were modeled using synthetic configurations. The solutions were evaluated using a composite objective function and a system of penalties for constraint violations.

Results. The results identify AI models that are optimal for ranking alternatives under a fixed computational budget and provide a stable ordering of solutions. For Random Forest, the achieved R² values are in the range of 0.995–0.999. A practical compromise between optimality and admissibility was identified, with the proportion of admissible solutions being significantly affected by the selection method and mode, ranging from approximately 39 to 99 % in certain scenarios.

Conclusions. The study identified optimal AI models that enable the generation of planning solutions, the calculation of quality and admissibility indicators, and the comparison of methods using unified evaluation rules. This supports the early-stage assessment and management of investment and construction project indicators.

Introduction. High rates of motorization in megacities, combined with a persistent shortage of parking spaces, necessitate the implementation of large-scale parking infrastructure projects. Such projects entail significant regulatory, investment, and urban planning risks, which require improved assessment approaches. Since these risks are interrelated and may have a cumulative effect on project outcomes, an integrated risk assessment approach is needed. The objective of this study is to develop an approach to the integrated risk assessment of parking space development projects in megacities.

Materials and methods. The study draws on international and Russian practical experience, regulatory and technical documentation, as well as scientific literature. The methods applied include systematization, analysis, decomposition, comparative analysis, target analysis, and matrix analysis. A risk classification pattern was developed, life-cycle stages and target parameters were identified, and a risk matrix was constructed.

Results. The study resulted in the development of a four-stage integrated approach for the quantitative assessment of risks associated with parking space development projects in megacities. The proposed approach includes standardization and strategic weighting of initial expert assessments of the impact of risks using project target parameters; calculation of an integrated risk indicator based on the probability of risk occurrence, strategically weighted impact and manageability; aggregation of risks by life-cycle stages, yielding summary indicators for each stage and an overall project risk indicator; and grouping of risks by project target parameters, with integrated risk indicators calculated for each parameter. A distinctive feature of the proposed approach is the simultaneous consideration of two complementary dimensions of risk aggregation — by life-cycle stages and by project target parameters — which makes it possible to distinguish between tactical and strategic levels of management.

Conclusions. The developed approach enables quantitative risk assessment, enabling risk aggregation by lifecycle stages and target parameters. Unlike discrete analysis of individual risks, this approach generates a system of indicators for tactical resource allocation and strategic prioritization. The results can be used to substantiate management decisions and implemented in the practice of managing parking space development projects in megacities.